This embodiment relates to an autostereoscopic display apparatus having parallax in one dimensional direction.
A technology is known, in which display images change depending on positions from which the display images are viewed, using special optical members such as a lenticular lens, a slit-type barrier, and a lens array, by dividing and presenting the image displayed on a display device such as a print surface or a liquid crystal display panel in multiple viewpoint directions. As a technique using the above technology, there is one that makes the image viewed stereoscopically by inputting, to a right eye and a left eye of a person viewing the display device, a display image which consists of the same object but differ from each other (parallax images) by having specific parallax. Using the stereoscopic viewing technique, an autostereoscopic display apparatus can be put into practice, which does not require any special glasses to achieve the stereoscopic viewing.
In a case of making an image viewed stereoscopically by the autostereoscopic display apparatus, there is need to increase a number of viewpoints by dividing the display image as much as possible, in order to expand a viewing region in which the image can be viewed stereoscopically, and to obtain natural stereoscopic effect and smooth motion parallax with which viewers can endure for a long time. Recently, targeting improvement in visual confirmation and the like regarding eye-catching items and stereoscopic information in a display device with a relatively low resolution such as a digital signage and a car navigation device, the stereoscopic viewing using the parallax images has been gradually introduced. The greater the number of viewpoints becomes, the lower the resolution becomes. It should be noted that resolution is defined as a physical property inherent in a display device itself, and resolution feeling is defined as a degree of resolution perceived by a person. Even in a case of making the display image stereoscopically in the low resolution display device, there is also need to suppress the lowering of resolution and to achieve the natural stereoscopic viewing.
To fulfill the above needs, a multiple view system is effective, in which viewpoints are divided as finely as possible, instead of dividing the viewpoints by assuming an eye position of a viewer who views the display device in a space, so that the viewer can view the display device with any of viewpoints. In order to increase the number of division of the parallax image, it is effective to increase, for example, a lens pitch in a case of using the lenticular lens with respect to a pixel pitch of the display device. However, by enlarging effect of the lens, respective color pixels become large relative to the lens pitch, degrading the resolution of the parallax image in a pitch direction of the lens. This makes the resolution feeling different in horizontal and vertical directions. The same influence appears in a case of using the optical member such as the barrier.
A technique is disclosed in Japanese Patent No. 3940456 (Patent Document 1) to solve the above trouble. Here, a periodical direction of cylindrical lenses (optical lenses) configuring a lenticular lens (optical member) is inclined with respect to the horizontal direction of a pixel array of a display device. With the technique of Patent Document 1, one three-dimensional pixel is configured using pixels of the vertical direction as well as pixels of the horizontal direction, improving balance of the resolution feeling between the horizontal and vertical directions.